2 questions on propranolol

[Nocturne031]

I'm used to a pounding heart beat, I must say I went into a panic when I couldn't hear my heartbeat after I took one... Checked my pulse in my neck and it was fine... But I can't feel anything in my chest... I'd say it was maybe 50 beats per minute? Is this ok?

I take 40mg on occasions, how long does it take for one tablet to leave my system?

Thanks in advance